Content Delivery Architecture

Delivering content to millions of globally distributed users with consistent sub-100 ms latency requires more than provisioning compute in a single region. AWS Solutions Architects at the professional level must design content delivery architectures that combine edge caching, edge compute, origin security, and intelligent failover into a unified system. Amazon CloudFront operates across more than 450 edge locations and 13 regional edge caches, placing cached content close to end users while shielding origins from direct exposure. The fundamental architecture pattern positions CloudFront as a reverse proxy in front of origins such as Amazon S3 buckets, Application Load Balancers, or custom HTTP endpoints. This design delivers three compounding benefits: reduced latency through edge proximity, decreased origin load through intelligent caching, and improved security through edge-based filtering with AWS WAF.

Architects must clearly distinguish between HTTP content-caching scenarios suited for CloudFront and TCP/UDP acceleration scenarios that require AWS Global Accelerator. This lesson focuses exclusively on the content delivery layer. The subsequent lesson on Traffic Optimization Strategies covers network-path acceleration where caching provides no benefit.

The following diagram illustrates the complete content delivery architecture with security boundaries, failover mechanisms, and request flow from global users through edge locations to secured origins.

CloudFront cache behaviors and origin design

Designing an efficient CloudFront architecture requires more than simply placing content behind a CDN. Architects must determine how requests are routed, which content should be cached, how cache keys are constructed, and how origins are protected from unnecessary load. These decisions directly affect cache hit ratios, latency, origin cost, and application correctness.

Cache behavior routing and key composition

CloudFront distributions use cache behaviorsordered rules that match incoming request URL path patterns and determine which origin receives the request, what gets cached, and how long content remains at the edge. The default cache behavior handles all unmatched paths, while additional behaviors route specific patterns to dedicated origins. A typical production configuration routes /api/ requests to an ALB origin for dynamic processing while directing / static asset requests to an S3 origin.

Cache key composition determines whether two requests share a cached response or generate separate origin fetches. The cache key can include combinations of URL path, query string parameters, HTTP headers, and cookies. Improper cache key design creates two failure modes: including too many variables fragments the cache and reduces hit ratios, while excluding necessary variables serves incorrect content to users who expect personalized responses.

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